<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>ResultConverter</title>
<link rel="stylesheet" href="../../boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="../index.html" title="Boost.Python Reference Manual">
<link rel="up" href="../concepts.html" title="Chapter 1. Concepts">
<link rel="prev" href="holdergenerator.html" title="HolderGenerator">
<link rel="next" href="objectwrapper.html" title="ObjectWrapper">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="" width="" height="" src="../../images/boost.png"></td></tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="holdergenerator.html"><img src="../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../concepts.html"><img src="../../images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="objectwrapper.html"><img src="../../images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="concepts.resultconverter"></a><a class="link" href="resultconverter.html" title="ResultConverter">ResultConverter</a>
</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="resultconverter.html#concepts.resultconverter.introduction">Introduction</a></span></dt>
<dt><span class="section"><a href="resultconverter.html#concepts.resultconverter.resultconverter_concept_requirem">ResultConverter
        Concept Requirements</a></span></dt>
<dt><span class="section"><a href="resultconverter.html#concepts.resultconverter.resultconvertergenerator_concept">ResultConverterGenerator
        Concept Requirements</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="concepts.resultconverter.introduction"></a><a class="link" href="resultconverter.html#concepts.resultconverter.introduction" title="Introduction">Introduction</a>
</h3></div></div></div>
<p>
          A ResultConverter for a type <code class="computeroutput"><span class="identifier">T</span></code>
          is a type whose instances can be used to convert C++ return values of type
          <code class="computeroutput"><span class="identifier">T</span></code> <code class="computeroutput"><span class="identifier">to_python</span></code>.
          A ResultConverterGenerator is an MPL unary metafunction class which, given
          the return type of a C++ function, returns a ResultConverter for that type.
          ResultConverters in Boost.Python generally inspect library's registry of
          converters to find a suitable converter, but converters which don't use
          the registry are also possible.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="concepts.resultconverter.resultconverter_concept_requirem"></a><a class="link" href="resultconverter.html#concepts.resultconverter.resultconverter_concept_requirem" title="ResultConverter Concept Requirements">ResultConverter
        Concept Requirements</a>
</h3></div></div></div>
<p>
          In the table below, <code class="computeroutput"><span class="identifier">C</span></code> denotes
          a ResultConverter type for a type <code class="computeroutput"><span class="identifier">R</span></code>,
          <code class="computeroutput"><span class="identifier">c</span></code> denotes an object of
          type <code class="computeroutput"><span class="identifier">C</span></code>, and <code class="computeroutput"><span class="identifier">r</span></code> denotes an object of type <code class="computeroutput"><span class="identifier">R</span></code>.
        </p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                  <p>
                    Expression
                  </p>
                </th>
<th>
                  <p>
                    Type
                  </p>
                </th>
<th>
                  <p>
                    Semantics
                  </p>
                </th>
</tr></thead>
<tbody>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">C</span> <span class="identifier">c</span></code>
                  </p>
                </td>
<td>
                </td>
<td>
                  <p>
                    Constructs a <code class="computeroutput"><span class="identifier">c</span></code>
                    object.
                  </p>
                </td>
</tr>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">c</span><span class="special">.</span><span class="identifier">convertible</span><span class="special">()</span></code>
                  </p>
                </td>
<td>
                  <p>
                    convertible to <code class="computeroutput"><span class="keyword">bool</span></code>
                  </p>
                </td>
<td>
                  <p>
                    <code class="computeroutput"><span class="keyword">false</span></code> iff no conversion
                    from any <code class="computeroutput"><span class="identifier">R</span></code> value
                    to a Python object is possible.
                  </p>
                </td>
</tr>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">c</span><span class="special">(</span><span class="identifier">r</span><span class="special">)</span></code>
                  </p>
                </td>
<td>
                  <p>
                    convertible to <code class="computeroutput"><span class="identifier">PyObject</span><span class="special">*</span></code>
                  </p>
                </td>
<td>
                  <p>
                    A pointer to a Python object corresponding to <code class="computeroutput"><span class="identifier">r</span></code>,
                    or <code class="computeroutput"><span class="number">0</span></code> iff <code class="computeroutput"><span class="identifier">r</span></code> could not be converted <code class="computeroutput"><span class="identifier">to_python</span></code>, in which case <code class="computeroutput"><span class="identifier">PyErr_Occurred</span></code> should return
                    non-zero.
                  </p>
                </td>
</tr>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">c</span><span class="special">.</span><span class="identifier">get_pytype</span><span class="special">()</span></code>
                  </p>
                </td>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">PyTypeObject</span> <span class="keyword">const</span> <span class="special">*</span></code>
                  </p>
                </td>
<td>
                  <p>
                    A pointer to a Python Type object corresponding to result of
                    the conversion, or <code class="computeroutput"><span class="number">0</span></code>.
                    Used for documentation generation. If <code class="computeroutput"><span class="number">0</span></code>
                    is returned the generated type in the documentation will be object.
                  </p>
                </td>
</tr>
</tbody>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="concepts.resultconverter.resultconvertergenerator_concept"></a><a class="link" href="resultconverter.html#concepts.resultconverter.resultconvertergenerator_concept" title="ResultConverterGenerator Concept Requirements">ResultConverterGenerator
        Concept Requirements</a>
</h3></div></div></div>
<p>
          In the table below, <code class="computeroutput"><span class="identifier">G</span></code> denotes
          a ResultConverterGenerator type and <code class="computeroutput"><span class="identifier">R</span></code>
          denotes a possible C++ function return type.
        </p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                  <p>
                    Expression
                  </p>
                </th>
<th>
                  <p>
                    Requirements
                  </p>
                </th>
</tr></thead>
<tbody><tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">G</span><span class="special">::</span><span class="identifier">apply</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
                  </p>
                </td>
<td>
                  <p>
                    A ResultConverter type for <code class="computeroutput"><span class="identifier">R</span></code>.
                  </p>
                </td>
</tr></tbody>
</table></div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2002-2005, 2015 David Abrahams, Stefan Seefeld<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="holdergenerator.html"><img src="../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../concepts.html"><img src="../../images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="objectwrapper.html"><img src="../../images/next.png" alt="Next"></a>
</div>
</body>
</html>
